Minimum Rotations Required to Get the Same String in C++

Problem statement

Given a string, we need to find the minimum number of rotations required to get the same string

Example

If input string is “bbbbb” then minimum 1 rotation is required

Algorithm

1. Initialize result = 0
2. Make a temporary string equals to original string concatenated with itself.
3. Take the substring of temporary string of size same as original string starting from second character i.e. index 1
4. Increment the counter
5. Check whether the substring becomes equal to original string. If yes, then break the loop. Else go to step 2 and repeat it from the next index

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
int getRotationCount(string str) {
   string temp = str + str;
   int n = str.length();
   for (int i = 1; i <= n; ++i) {
      string sub = temp.substr(i, str.size());
         if (str == sub) {
            return i;
         }
   }
   return n;
}
int main() {
   string str = "bbbbb";
   cout << "Rotation count = " << getRotationCount(str) <<
   endl;
   return 0;
}

When you compile and execute above program. It generates following output

Output

Rotation count = 1